C# - Is it possible to have null params?

Question

public void Foo(params string[] values) { } 

Is it possible that values can ever be null, or will it always be set with 0 or more items?

Answer 1

Absolutely - you can call it with an argument of type string[] with a value of null:

string[] array = null; Foo(array); 

Answer 2

I decided to write some code up to test this for myself. Using the following program:

using System;  namespace TestParams {     class Program     {         static void TestParamsStrings(params string[] strings)         {             if(strings == null)             {                 Console.WriteLine("strings is null.");             }             else             {                 Console.WriteLine("strings is not null.");             }         }          static void TestParamsInts(params int[] ints)         {             if (ints == null)             {                 Console.WriteLine("ints is null.");             }             else             {                 Console.WriteLine("ints is not null.");             }          }          static void Main(string[] args)         {             string[] stringArray = null;              TestParamsStrings(stringArray);             TestParamsStrings();             TestParamsStrings(null);             TestParamsStrings(null, null);              Console.WriteLine("-------");              int[] intArray = null;              TestParamsInts(intArray);             TestParamsInts();             TestParamsInts(null);             //TestParamsInts(null, null); -- Does not compile.         }     } } 

The following results are yielded:

strings is null. strings is not null. strings is null. strings is not null. ------- ints is null. ints is not null. ints is null. 

So yes, it is entirely possible for the array associated with params to be null.